M-38 Help in Phoenix

[blitz67]

My father lives in anthem, Arizona and is nearing 80 years old, he has had an M-38 for about thirty years, he had the engine rebuilt about 22 years ago. Ever since he had it rebuilt he has had over heating issues. He has tried everything to his ability to resolve this with no joy. I live in Northern California and can't get down there long enough to help him, he doesn't have a lot of tools and he doesn't know much about engines and mechanical stuff. Can anyone tell me of a shop or mechanic in the phoenix area that I can trust to get his Jeep on the road? As far as the engine over heating, the real problem I believe is that the guy who rebuilt his engine may have over bored it or screwed something else up internally. He already has 22 years on the engine which he drives a lot, I told him to pull it and have it rebuilt, sleeved back to standard, etc. Thanks for any help

Brad

[4X4M38]

Hi Brad,
There are some things you can check without pulling the engine.

Confirm the temperature with a separate gauge or thermometer.

Open the radiator cap before start up. Get it running and watch the
water in the filler neck. Once it gets to close to operating temp 165-185
depending on the thermostat, watch for the water to begin circulating
through the radiator. If it doesn't circulate the thermostat is bad or the
wrong thermostat, or the water pump could be bad.

No circulation could also mean a partially or completely plugged radiator.
When he had the engine rebuilt was the radiator give through?

What does the radiator fluid look like and does it have the proper mix of water
to antifreeze?

Try these and let us know what you find.

Take care,
Brian

[blitz67]

Brian, thanks for the help. He has an older repro radiator from Rapco that is way too thin, so that is the first thing he needs to do, I had him pull the thermostat elbow, the thermostat was jammed in there so bad we had to cut it out, I got him a new nos elbow and a new correct thermostat and still overheats. This has been going on for years, at this point I really think he just needs to buy a new radiator first, but pull the head and just take a look inside and see what its bored too, I know the guy that rebuilt the engine and he is not a Jeep guy and did it in his spare time in a trade deal with my father. The problem is that he can barley change a spark plug, so I need to find him someone that knows Jeeps. He has taken it to so many different people and no one seams to know what they are doing.

[dpcd67]

I would work on the cheap (relatively) parts first, meaning the radiator; if it has fewer rows than original, then get another one. . And make sure he has antifreeze in it; not plain water. Also, what temp does it run at? As long as it is not boiling, then it is ok. What is overheating, to you? Many jeeps run at 200 very well.

[blitz67]

Yea, I'm going to find him a new radiator first. Its running about 240 degrees. Sometimes it will run fine and then just spike and you have to shut it down

[DieFledermaus]

I have a used one that you could re-core.
-Mike in San Francisco area

[artificer]

Ever since he had it rebuilt he has had over heating issues. Like a full description?
As far as the engine over heating, the real problem I believe is that the guy who rebuilt his engine may have over bored it or screwed something else up internally.
He already has 22 years on the engine which he drives a lot, I told him to pull it and have it rebuilt, sleeved back to standard, etc.

I doubt that would be the issue & I definitely wouldn't be suggesting rebuilding the engine again, not knowing, your Dad may do that, then re-hook everything up & STILL have exactly the same problem because of a bad temperature gauge or blocked radiator, for example.

It is time to diagnose logically, not assume or guess.
Some things that have been mentioned....check the temperature gauge....pressure test the cooling system....check number of core rows in the radiator & flow rate....thermostat....coolant mix....& radiator cap can all be eliminated in <30 minutes.

Then we are checking the engine tune....hook up a vacuum gauge & dwell/tacho & lets know the readings he is getting.

http://www.vintageautorepair.net/custom ... s-and-50s/ Don't know these folks but others may?

[old stuff]

The OEM M38 radiator is thicker (think more cooling surface area) than some of the ones that is advertised to fit, like a CJ. They will probably fit and work but not as efficently.

[4X4M38]

Brad,
You haven't mentioned if the water pump is circulating fluid properly.

Brian

[blitz67]

Brian, the water pump is good. He has changed it four times. I checked it and it was pumping fine. At this point I think the radiator is the main suspect but I'm concerned that his engine is bored out way too much

I have a radiator on the way to him now, we will see. Thanks for all the help so far. Kind of tough to diagnose it from 1000 miles away but it can't be too complicated. Also checked thing and it is fine

[artificer]

Except for loose fan belts & leaking, water pumps are not related to overheating problems.

[4X4M38]

Hello John,
If the water pump is not circulating water will the engine not overheat?

Thanks,
Brian

[artificer]

If the water pump is not circulating water

I'm not sure how any water pump being turned by the fan belt is not circulating coolant.
In my years turning wrenches I have only once seen a waterpump with the impeller [the thing that turns & helps circulate the coolant] busted up.
The impeller was plastic & the bottom hose on this particular Chrysler vehicle had a spring inside the hose to stop the hose collapsing & causing cavitation. The spring rusted, broke up & in that process destroyed the impeller.

[4X4M38]

Oh, Lord I better get that rusted spring out of my bottom hose!